Learning to Drive in California: Patterns in Novice Motor

Vehicle Crashes and Traffic Violations in the Era of the Graduated Driver Licensing

Law

Scott Vincent MastenCalifornia DMV

Research & Development Branch

Center for Healthcare Policy

and Research Seminar Series

Have you (or your spouse/partner) had a personal financial relationship in the last 12 months with the manufacturer of the products or services that will be discussed in this CME activity?

___ Yes

_X_ No

(If yes, please state disclosures and resolutions)

Speaker’s VerbalDisclosure Statement

1. To describe how the crash rates of novice drivers change after licensure

2. To identify novice drivers with exceptionally high crash rates after the California graduated driver (GDL) licensing law was implemented

3. To discuss opportunities for reducing crash mortality and morbidity among age 18 and older novices

Educational Objectivesfor this Seminar

CDC, WISQARS, 2014

Motor Vehicle Crashes

Why should I care?

Over 2.7 million injuries per year

Leading cause of death for ages 13-25

Top 5 cause of death for ages 1-44

Motor vehicle crash

Heart diseaseCancer

Cerebrovascu-lar

Lower Respi-ratory Disease

SuicideAlzheimer's

Other injuryAll other

1.4%

All-Age Causes of Death

United States, 2010

CDC, WISQARS, 2014

CDC, WISQARS, 2014

Age 16-19 Causes of Death

United States, 2010

Motor vehicle crash

Heart diseaseCancerCerebrovascu-

lar

Lower Respi-ratory Disease

Suicide

Homicide

Other injury

All other

27.4%

FARS; 2000-2009

Fatal 16-19-Year-Old Crashes

United States, Annual

2,500 teen driver deaths (180 California)

1,600 teen passenger deaths (170 California)

10% of all crash fatalities are teens

0

50

100

150

200

16 17 18 19 20-24

25-29

30-34

35-39

40-44

45-49

50-54

55-59

60-64

65-69

70-74

75-79

80-84

85+

Driver Age (years)

Cra

sh

es p

er

1,0

00

Lic

ensed

Drivers

.

Crash Rates by Driver AgeUnited States, 2000

Crash rates decrease as age increases

Highest rates among teens 16-19

Many teens are just learning to drive (novices)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0 6 12 18 24 30 36 42 48 54 60

Months after Licensure (Ages 16-17)

Pe

rce

nta

ge H

avi

ng F

irst

Cra

sh

.

First Crash IncidenceEach Month After Licensed to Drive

Unsupervised

Novice teen crash rates decrease markedly during the first year

They continue to decrease at a slower rate for years

Even a little driving experience results in much lower crash rates

Graduated Driver Licensing (GDL) Reduce risk while experience

gained Implemented in all U.S.

jurisdictions Restrictions on novice teen

driving are gradually removed in three stages:1. Learner Stage

• May drive only with a licensed adult

2. Intermediate Stage• Unsupervised, but driving

restrictions:• Nighttime• Passengers, usually other teens

3. Unrestricted (full) Driving Stage

Graduated Driver Licensing and Fatal

Crashes Involving 16- to 19-Year-Old Drivers

Scott V. Masten, Robert D. Foss, & Stephen W. Marshall

Nationwide Evaluation of GDL

Design Pooled cross-sectional time series

Data Fatality Analysis Reporting System (FARS)

Driver fatal crash involvementsPassenger vehiclesAll states & D.C.1986-2007, quarterlyState-age group-quarters

Population data from the U.S. Census

Nationwide Evaluation of GDL

Analysis Poisson regression with GEEs

Separate models ages 16, 17, 18, 19, & 16-19

Control for non-GDL law changes, crude exposure, economic conditions

Trend & seasonality adjusted by state & age

Adult crash rate covariates - unmeasured confounders

U.S. Teen Fatal Crashes Post-GDL

Age 16 crashes lower under GDL

Age 18 crashes higher under GDL

Evaluation of the California Graduated

Driver Licensing (GDL) Program

Scott V. Masten & Robert A. Hagge

Note: Originally completed in 2004; updated data presented here

Implemented July 1998

Applies to all drivers licensed age <18

1. Learner Stage• Min age 15; 15½ starting 2004• 6 mo. mandatory learner permit• 50 hours supervised practice

2. Intermediate Stage (age ≥16)• Nighttime restriction - 12:00am-5:00am for 12 mo.

• 11:00pm-5:00am starting 2006• Passengers – None < age 20 for 6 mo.

• 12 mo. starting 2006

3. Unrestricted (full) Driving Stage• Min age 17; automatic at age 18

The California GDL Program

1. How did CA population-based teen crash rates change after GDL?

2. How did CA driver-based teen injury crash rates change after GDL?

3. How did CA licensure rates change after GDL?

Research Questions

Study Data

Statewide Integrated Traffic Records (SWITRS)

Driver injury crash involvementsPassenger vehicles1985-2011, monthly

Population data from the U.S. Census

License data from DMV

California Crashes, per capita

Age 16 crashes decreased after GDL

Age 18-20 crashes

increased after GDL

California Crashes, per driver

No decrease in age 16 crash rates per driver after GDL

Age 17-20 increased after

GDL

California Licensure Rates

Age 16-17 licensure decreased after GDL

Age 18-20 same or increased

after GDL

1. CA crashes mirror the nationwide GDL study

Lower crashes for younger teens Higher crashes for older teens

2. CA licensure rates after GDL: Lower for ages 16-17 Same or higher for ages 18-20

Study Conclusions

What’s going on with older CA teens after GDL?

Crash Rates of Teens Delaying Licensure

Compared with Those Not Delaying Licensure

Eric A. Chapman & Scott V. Masten

Nationally, GDL associated with higher 18–19-year-old fatal crash rates (Fell, Jones, Romano & Voas, 2011; Males, 2007; Masten, Foss, & Marshall, 2011; Masten & Hagge, 2003)

Possible mechanisms:

1. More 18–19 Novices: Delayed licensure to avoid GDL

2. Lower 18–19 Competency: GDL limits real-world driving experience

Study Background

1. Do CA teens appear to delay licensure to avoid GDL?

2. How do CA teens who delay licensure drive compare to their same-age peers?

3. How do CA teens who delay licensure compare to novices of other ages?

Research Questions

Data Random 10% of CA newly-licensed (novices),

1999–2007 (post-GDL) 3-year total & fatal/injury crashes

Analyses Age of novice CA licensure Novices vs. same-age peers licensed 1 or 2 years

prior Separate Poisson models 18, 19, 20, 21–24, & 25–35

Different-aged novices vs. each other

Method

Age of Novice Licensure, 1999-2007

Fewer at 17, suggesting…

Delayed licensure until 18

Most novices at 16 or 18

Age 18 Novices vs. Age 18 Experienced

Licensed at 18 (avoided GDL)

Licensed at 17 (GDL)

Licensed at 16 (GDL)

Note: Rates adjusted for sex, year, & month of licensure.

Age 19 Novices vs. Age 19 Experienced

Licensed at 19 (avoided GDL)

Licensed at 18 (avoided GDL)

Licensed at 17 (GDL)

Note: Rates adjusted for sex, year, & month of licensure.

Age 20+ Novices vs. Age 20+ Experienced

Age 20

Ages 21-24

Experience associated with fewer crashes for all ages…

Novices of all ages are worse drivers than same-age peers.

Ages 25-35

Novices of Different Ages (Total Crashes)

18 novices start out worse than everyone…

Even younger novices

16171920

21-24

25-35

18

One age group does not fit the pattern

Drop

Note: Rates adjusted for sex, year, & month of licensure.

Novices of Different Ages (Fatal/Injury)

16

17

20

21-24

25-35

Again 18 novices are worse than everyone1

8

Does this explain the higher 18-19 crash rates after CA GDL?

Drop

19 novices also bad19

Note: Rates adjusted for sex, year, & month of licensure.

Do CA teens appear to delay licensure to avoid GDL?

Yes:

Fewer teens licensed at 17

Licensure pops up again at 18

Research Question #1

How do CA teens who delay licensure drive compare to their same-age peers?

They have higher crash rates:

CA 18 and 19 year-olds who delay licensure crash more than their same-aged peers…

But this is true for novices of all ages compared to their same-age peers

Research Question #2

How do CA teens who delay licensure compare to novices of other ages?

They have higher crash rates:

Delaying 18 year-olds have higher total and fatal/injury crash rates than other novices.

Delaying 19 year-olds have higher fatal/injury crash rates than other novices.

Research Question #3

Some CA teens appear to delay licensure until age 18: No GDL or driver education.

18-19 novices who avoid GDL are worse than ALL other novices, even younger teens

Was this a result of implementing GDL?

All novices worse than their experienced peers: GDL may benefit novices of all ages.

Study Conclusions

Crash and Traffic Violation Rates Before and After

Licensure of Novice California Drivers Subject to Different

Driver Licensing Requirements

Eric A. Chapman, Scott V. Masten, & Kelly K. Browning

When novice teens begin to drive unsupervised their crashes increase radically, even under GDL programs (Lewis-Evans,

2010; Mayhew et al., 2003; VicRoads, 2008)

Crash rates decrease dramatically within the first months of licensure, but remain high vs. older novices (Lewis-Evans, 2010; Masten & Foss, 2010; Mayhew

et al., 2003; Twisk & Stacey, 2007; VicRoads, 2008)

Inexperience may cause high initial crash rates; teen rates may remain elevated because of overconfidence (Ericsson, Krampe, & Tesch-Römer,

1993)

Study Background

1. How do crash and traffic violation rates of novice CA 16–17-year-old drivers licensed under GDL change over time?

2. How do the rates for novice drivers age 18 and older not licensed under GDL change over time?

3. How do the types of traffic violations vary during the course of licensure?

Research Questions

Data All novices licensed in CA at age 16 or 17 (2001-2007) 10% sample of all age 18 to 35 novices (2001-2007) 3-year post-licensure crashes and traffic violations

Traffic violations categorized as inexperience-related vs. overconfidence-related

Analyses Length learner permits are held by age Crash and traffic violation rates over time

Overall & subtypes (e.g., fatal/injury, inexperience)

Separate Poisson models 16, 17, 18, 19, 20, 21–24, 25–35

Method

Learner Permit Holding by Age

Majorities of age 16 (57%) and age 17 (73%) hold learner permits longer than the required 6 months

31% of age 16 and 49% of age 17 hold permits for 9+ months

Majorities of age 18+ novices hold learner permits less than 6 months

Total Crash Rates

Crash rates for all novices decrease most during 1st year of driving

Peak rates typically 2nd or 3rd month

Age 18+ ramp-up of crashes before licensure

Fatal/Injury Crash Rates

Age 18 and 19 novices initially crash more than younger novices

Pre-licensure rates highest for age 18+

1. Crash rates of most novices are highest immediately after licensure

2. They decline quickly during their 1st year

3. Then decline slower for the 2nd and 3rd years

Crash Rate Findings

Just like classic learning curves

4. Post-licensure crashes are higher for some age 18+ novices than those for ages 16–17

5. Pre-licensure crash rates for age 18+ novices ramp up immediately before licensure

Suggests they try to learn to drive during a very short time period

Contrary to good learning methods (spaced practice)

6. 70% of age 16–17 novices are crash-free for the first 3 years of licensure

Crash Rate Findings (cont)

Total Traffic Violation Rates

Traffic violations for age 16 and 17 novices peak long after their crashes, around the time when they are age 18

Age 18+ violations highest during 1st year or pre-license

Wow

Inexperience vs. Overconfidence Violations

Age 16-17: inexperience & overconfidence violations peak after crashes, when

they turn age 18

Age 18+: inexperience and overconfidence violations peak 1st year of licensure, when crashes peak too

Inexperience

Overconfidence

1. Age 16–17 novices’ traffic violation rates peak long after their crashes peak (when age 18)

2. Violation rates for age 18+ novices peak during their 1st year of licensure.

3. Inexperience and overconfidence violations typically peak around the same time

4. 45% of age 16–17 novices are traffic violation-free for the first 3 years of licensure

Traffic Violation Rate Findings

1. Age 16–17 novices typically hold learner permits for longer than minimum 6 mo.

2. Older CA novices appear to rush learning to drive; do not hold permits very long

3. Novices driver crash rates for most ages follow a classic learning curve

4. Novice driver violation rates do not follow a classic learning curve—proxy for exposure

Study Conclusions

1. To describe how the crash rates of novice drivers change after licensure

• Pattern follows classic learning curve

• Highest immediately after licensure

• Decrease dramatically during the 1st year

• Decrease at a slower rate subsequently

Review of Educational Objective #1

2. To identify novice drivers with exceptionally high crash rates after the California graduated driver (GDL) licensing law was implemented

• Age 18-20 crashes increased after GDL

• Age 18-19 crash rates now higher than all other novices, even younger teens

Review of Educational Objective #2

3. To discuss opportunities for reducing crash mortality and morbidity among age 18 and older novices

• Given that age 18+ novices appear to cram learning to drive into a short period…

• Maybe they would benefit from minimum learner permit holding periods

• Given that age 18+ novices are also worse than their experienced peers…

• Maybe they would benefit if GDL was extended to them, particularly for ages 18-20

Review of Educational Objective #3

Thank you!

Questions & Discussion

Scott V. MastenScott.Masten@dmv.ca.go

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